Britain's new rock star

Here are three things to know about Britain's general election. The shifts in voter opinion during the opening stages of the campaign have been as big as any seen since the pollsters started counting. If things stay roughly as there are, the third party Liberal Democrats are heading for their best result since 1923. If that were to happen, the May 6 election would rewrite the rules of British politics.

Now for a fourth: no one knows what is going to happen next. Commentators, including this one, need to show more than a smidgen of humility and caution: humility because past predictions have been up-ended by Nick Clegg's elevation to the status of political rock star; caution because the volatility of public opinion could see a violent shift in one direction followed by an equally unexpected reversal.

The Lib Dems owe their good fortune – recent polls put them in second place to David Cameron's Conservatives – to Clegg's strong performance in the first of three televised debates. Much now depends on the public response to the second contest and to a third next week. Simply put, a campaign with two weeks to run has become as impossible to predict as it is fascinating to describe.

Everyone knew that the debates had the capacity to change the dynamics of the election. This was the first time, after all, that British voters would see their political leaders go head-to-head so close to polling day. It was also clear that the 43-year-old Clegg would profit from the equal billing and exposure usually denied his party. Yet the unexpected scale of the public applause for Clegg's performance (Lib Dem support rose from about 20 to 30 per cent) suggests voters were doing more than choosing a winner of a beauty contest.

The country is unaccustomed to elections like this. True, there was a period during the 1970s when the two big parties had only a weak grip on power. A minority Labour government was briefly propped up by the then Liberals in what was called the Lib-Lab pact. But for the past three decades, the Conservatives and Labour have shared the spoils. Margaret Thatcher's 1979 victory gave the country 18 years of Tory rule; Tony Blair's big win in 1997 ushered in 13 years of Labour dominance.

And now? Gordon Brown's faltering administration has become little more than a bystander in the campaign. The prime minister has struggled vainly to put his message across as Messrs Cameron and Clegg have battled it out to claim the mantle of the change candidate.

The big issues that were supposed to dominate the argument on the stump, notably about how best to repair a ruinous hole in the nation's public finances, have been largely forgotten. The parties, an adviser to Brown confides, are "filling in time between the debates”.

The campaign is now largely about what voters think of politics and politicians. The answer in the wake of a painful recession and the furore about the misuse by MPs of parliamentary expenses is not very much. Clegg's good fortune, or some might say genius, has been that of a party politician who has seized the leadership of the anti-politics party.

This was not a role he was born to. Clegg is every bit an establishment figure, the scion of a wealthy banker and an alumnus of one of Britain's most expensive schools. He toyed with joining the Conservatives before signing up as a Lib Dem. His politics are to the right of most of his party's footsoldiers. As for policies, he has some sensible ideas about civil liberties and foreign affairs, and some barmy ones about taxes.

No matter. As the self-styled outsider, Clegg has perfected a "there-you-go-again” piety when attacked by what he cheekily calls the "old” parties. His success has also exposed a fragility in Cameron's claim to have remade the Tories as a centrist party in tune with the concerns of voters.

It has been evident for the past two years that the electorate had concluded Labour had had its day; it has also been clear that they were cautious about leaning too enthusiastically towards the Tories. Poll ratings of close to 40 per cent seemed enough to install Cameron in Downing Street, but only just. Now those ratings have fallen to the mid-30s, a level that would deny him a parliamentary majority.

If the campaign ends roughly where it is now, the election will deliver two sets of political shocks. Most immediately, in the absence of a clear winner the vote-counting will give way either to a minority government or to some form of coalition at Westminster. Because of the urgent need for a credible medium strategy to reduce the nation's budget deficit, protracted negotiations between the parties could lead to some awkward moments on the financial markets.

Depending on the nature of any bargain struck between the parties – whether a Lib-Con pact or a Lib-Lab understanding – there would also be the real possibility of an early second election. In 1974, the last time there was no outright winner, there were two elections in nine months.

The bigger significance of a hung parliament, however, would lie in its likely impact on Britain's political system. The surge in support for Clegg's party has shone a light on the absurdities and iniquities of the electoral system that has so long denied it a share of power.

Designed to accommodate two parties, the system is now being stretched out of shape by the success of the third. Such are the perverse consequences that if the votes on May 6 were shared as the latest polls suggest – about 32 per cent for the Tories, 30 per cent for the Lib Dems and 28 per cent for Labour – Brown could still emerge as the leader of the largest party in the House of Commons. Clegg, with almost as many votes as Cameron, might end up with less than half the number of seats.

The voters would not accept the legitimacy of such an outcome. Brown has signalled he is ready to see a more proportional electoral system; Cameron would be under intense pressure to follow suit.

The small "c” conservative in me still thinks that the last lap of the campaign could yet see things drift back to roughly where they started. In the end, the British tend to play safe. But the fact that no one any longer can be sure may be a sign of just how much things have changed.